Design and fabrication of AlGaAs/GaAs phase couplers for optical integrated-circuit applications

As integrated electronic circuits based on GaAs are getting faster and more complex and the relatively new fiber optic communication industry is expanding into new markets, such as shipboard communication links, the need for high-speed optical signal processing in a GaAs-based system has become increasingly evident. The economy and flexibility of fabricating both electronic and optical circuits on the same wafer promises significant increases in the computing power and speed of large distributed systems (those involving more than a few medium-density chips). The obvious medium for integration of optics with electronics is GaAs. High-speed ICs utilizing GaAs MESFETS are already in the marketplace, as are GaAs/AlGaAs laser diodes and detectors. Thus the two building blocks exist and only wait to be stacked together in a useful manner. What must hold these together is any combination of passive waveguides, modulators, switches, or optical fibers which will provide high-speed links between several electronic systems. It does not matter that these systems may be miles apart or on the same wafer: the interconnecting optical circuits are the same except for the possible insertion of an optical fiber.